Spain's second city is so effortlessly attractive that it's hard to believe anyone could fall out of love with it. A new documentary called Bye Bye Barcelona, however, shows some long-term residents wondering aloud how much longer they can stay where they are. The problem? Tourism, specifically a local industry that has become so dominant it risks stifling ordinary, everyday life in the city's heart. Panning across street after street of pedestrian gridlock, fast food joints and souvenir shops, the film's record of locals shooed away by the constant visitor footfall offers a cautionary tale for any city that tourists love.

What makes Bye Bye Barcelona so striking is that its subject has long been an international role model for harbor cities trying to reinvent themselves. Following the 1992 Olympics' promotional boost and a revamp of the waterfront, Catalonia's capital built a reputation as the perfect Mediterranean city for visitors. Both grand and intimate, Barcelona has narrow old streets (until recently, populated by ordinary people) that lie minutes from elegant squares and promenades, as well as a manageable size, tolerable crime rates and a metro that works. It offers both high art and nightlife continuing well after dawn, and if you've had your fill of Gaudi's swirls and ripples, there are always beaches near at hand. Europe's worst kept secret, Barcelona’s visitor numbers shot up from 1.7 million visitors annually in 1990 to 7.4 million in 2012.

Europe's worst kept secret, Barcelona’s visitor numbers shot up from 1.7 million visitors annually in 1990 to 7.4 million in 2012.

Thanks to this yearly stampede, money has poured into the city (albeit not into everyone’s pockets) transforming working-class areas like El Born and La Barceloneta into visitor honeypots. Given Spain's shaky economy, the money is welcome – but it comes at a cost. So great has tourism's dominance of Old Barcelona become that the area risks becoming a monoculture, a place where tourism-geared businesses and constant crowds pushes regular shops and the locals who use them out, freeing up space for yet more of the same.

As Bye Bye Barcelona notes, this displacement has been forced and ugly in some extreme cases. Take the story of an old man driven from his flat by prospective hotel owners, who arranged for people to defecate on his doorstep daily. Meanwhile, severe overcrowding at the Gaudi-designed Park Güell has led to drastic action from the state – they've started charging an €8 entrance fee to everyone but immediate neighbors. This may well be the least bad solution, but for many the sight of a public park being cordoned off and admission charged confirms their gut feeling that their home city is quickly becoming, if not already, an urban theme park.

Such rough handling has certainly changed the city from the one I knew growing up, when I used to visit regularly. Back then, the Old City was a cheap, if somewhat sketchy place to live. The city’s showcase avenue, La Rambla, was busy but not overly busy, packed variously with booksellers, produce markets or caged songbirds for sale and lined with real bars you’d actually want to go to. Now? Don’t even think about it. The avenue has become a seamless souvenir emporium, solid with bodies in high season, full of businesses chasing easy bucks by selling Mexican sombreros and Valencian Paella, neither of which have much to do with Barcelona.

Many Barcelona visitors want – and get – far more than this, of course. More people are attracted by good food and architecture than by cheap cava and Barça football T-shirts. If you move away from La Rambla there are still great neighborhoods – such as Poble-Sec, Sant Antoni, Gràcia, and much of El Raval – that have kept their character. Tellingly, none of the contributors to Bye Bye Barcelona are actually against tourism per se. Their chief ire is directed at a city government whose planning laxity risks sapping away at the urban vitality that attracts visitors to Barcelona in the first place. It’s an opinion worth taking note of. Old neighborhoods that cater overwhelmingly to tourists soon start to feel like Potemkin villages, historic shells where residents either resign themselves to being penned-in local color, or flee.